Washing of fabric articles is a commonly used process throughout the world. A specific problem with all machine wash processes is that machine washing processes do not always remove stains on fabric articles. In hand wash processes, special attention can be provided to stains, but in washing machines this attention is generally absent.
One way of making sure that stains are removed is the application of a pre-treatment composition onto the stain, prior to the start of the washing process. Another way is to manually remove the stain before washing. Both methods are commonly used in the art.
Another way of pre-treatment is the use of a water sprays to utilise hydrodynamic stress for the removal of stains. Sprays, generally defined as either high speed liquids e.g. water, or a combination of water and air, have been used to clean hard and non-porous surfaces e.g. automobiles, walls and, metallic vessels.
U.S. Pat. No. 4,787,404 (IBM, 1988) discloses a low flow-rate pressure atomizer device which is so dimensioned and operated as to accelerate a gas to substantially sonic velocity and cause it to break up a cleaning liquid. It also discloses input at a high pressure into small droplets and acceleration of these droplets to at least half the velocity of said gas, to create shear stress at a surface adjacent the exit end of said device, thereby removing the contaminants from said surface.
FR-B-1108989 discloses a process to clean a substrate by subjecting the substrate to an air-water spray generated by a spraying means comprising an air passage and a water passage.
US 2002/189641 discloses a device for cleaning a soiled surface, the device comprising a feed water container and an air compressor in communication with the spray nozzle comprising a water passage and an air passage.
Both of the above mentioned devices provide an air water spray that is mixed inside the device. The disadvantage of such system is that the water flow cannot be reliably regulated because the air pressure goes against the direction of the water flow. This is especially problematic when a low water-to-air ratio (for instance in water:air ratios of less than 1:9) is required or a low water flow-rate if used. The nozzles of the prior art are not suitable for this purpose.
EP 0 140 505 discloses an industrial component fluid let having a nozzle comprising two coaxial tubes. The outer tube has a stepped bore. An annular swirl plate is spiqotted into an intermediate diameter bore portion and has an end of the inner tube spiqotted into it. Cleaning fluid passed through the swirl plate emerges into a chamber with an axial directional component and a spinning action to form a hollow cone spray. Fluid emerging from the inner tube only forms a pinpoint iet but cooperates with spinning fluid emerging simultaneously from the swirl plate to form a solid cone jet. The let may be operated and orientated by a robot.
U.S. Pat. No. 4,569,483 discloses an apparatus using a low pressure water stream, from a tap source, into which chemicals can be selectively introduced, and a high pressure water stream produced by a pump, into which chemicals can be selectively introduced, and an air stream into which chemicals can be selectively introduced. A heated water supply provides water for the high pressure stream. All the streams lead to a single spray pistol, the spray pistol having control switches for controlling the lines and chemicals.
EP1250959 discloses a cleaning device with a single nozzle that uses an internally mixed air, water and soap mixture for cleaning at high pressure. This prior art has only one nozzle and it is internally mixed and not suitable for this purpose.
A specific way of pre-treatment, described in our co-pending application PCT/EP2009/050869 (published as WO2009/103595), is the use of an air-water jet to remove a stain from a fabric article. The air-water jet device as described comprises of a nozzle design for the external mix of air and water and a compressor for providing the required air.
However, hydrodynamic stress alone does not always provide the required result.
It is therefore an object of the present invention to provide air-water jet device for cleaning fabric articles with enhanced performance.
It is a further object of the invention to provide a dosing device for a detergent composition that may be connected to an air-water jet device.
Surprisingly it has been found that a dispensing chamber for a detergent composition between the water source and the outlet of the water nozzle provides improved cleaning of an air-water jet.